From Dust to Diamonds
by PurpleGummiBear3
Summary: AU Crossover - DI Catherine Rollins and Sergeant Emma Swan stumble upon a puzzling string of murder cases. Andrew (OC) is an energetic chemist who has no business on a crime scene but is going to be there anyways. The bodies are burned, but why is this killer so careless? And what the hell do diamonds have to do with anything? Set in modern day NY. Collaboration with kittykat7290.
1. Prologue

**AN: Hi! This is a collaboration story with kittykat7290. We originally wrote this for a chemistry assignment, but we had to throw in OUAT and H50 :) But of course, being the fangirls that we are, we had to add cameos of our other favorite fandoms. Me, being totally and eternally in love with BBC Sherlock wrote in Anderson - our lovable, annoying forensics guy. And kittykat7290 is completely obssesed with the Avengers, so look out for references! :) **

**Since this was for chemistry class - I know, we actually go points for it! - our OC is Andrew, and yes, he is based on our Chemistry teacher Andrew :) Okaaay I'm going to shut up now! **

**Enjoy the story!**

* * *

**Prologue**

Marian sighed as she flipped the sign on the Locksley bakery's front door. Business was slow today, as it normally is. She walked towards the back of the small building to start the process of cleaning all the flour and dough that was crusted on the kitchen counter tops.

She grabbed a rag and started to clean the countertops. Puffs of flour flew out everywhere and Marian's hair and clothes were covered with the fluffy baking substance. She went to work scraping the bits of dough crusted on her baking tools.

As labouring as this job was, Marian wouldn't be happy doing anything else. Ever since she was a little girl she wanted to own her own bakery. It didn't bring in much money, but it brought her a bout of happiness.

A small smile graced her lips as she worked, cleaning every inch of her little bakery shop.

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

1 hour and 30 minutes later everything was clean and how it should be, as Marian walked out into the main store to check the cash register. Her work had taken a lot meticulous concentration, so the sun had set before she finished scrubbing the flour from the floors.

All of the clean up took so long, Marian was seriously considering hiring extra help. She always likes to be able to control things, but this was getting a bit outrageous. Eventually her husband would get sick of her work hours being longer than his.

While Marian was covered head to toe with flour and dough, and she smelled like a big cookie, her bakery was spotless. She looked around in triumph before picking up her clipboard to go over tomorrow's shipments.

The holidays were at a bit of a lull right now, save Valentine's, but soon it would be March, and that always seems to be the month of birthdays. She would probably have to double her icing order with all the birthday cakes and everything.

Plus, all those trainee's always messed up or wasted too much icing when they try to pipe letters or designs. Another reason why Marian is reluctant hire more people to help. Sometimes, you just have to do things your self otherwise they're never done properly.

Suddenly the bell atop the door chimed as it was opened. Marian turned her head around towards the door, her butterfly hair clip sparkling as it hit the light.

"Sorry, we're clos- mph!"

The sound of a clipboard clattering on the floor was all that echoed around the quiet streets that night. Then, all was still.


	2. Chapter 1

**AN: So here starts the actual story :)**

* * *

**Chapter One**

Andrew Lerario lived a happy, simple life. He was devoted to his very mundane job that held a very mundane schedule. This consisted of regular handling of chemicals that can _and will_ melt skin off bone, the common explosions that can _and do_ threaten the lives around them, and the drawings of little particles that come together to create this little thing called _life. _Yes. It is all _very_ mundane.

But of course, this quaint style of life led him to meeting friends that were just as simple and calm. In fact, he was on his way to meeting one of them now.

"Table for one, sir?" The barista asked Andrew.

"Two actually, thank you," Andrew replied. The barista nodded and led him to a small table outside and handed him a menu. "Thanks,"

An old fashioned yellow bug pulled up to the curb next to the little cafe. Andrew looked up waving to the driver getting out of the car.

"Hey!" Emma Swan waved to Andrew, walking over.

"Hey Em," Andrew said, pulling out a chair for her.

Andrew had met Emma a few years back. She was just graduating from the police academy, a rookie they called her, and was assigned to work on a chemical explosion at Andrew's lab.

Andrew claimed no responsibility for the incident but Emma thought her super power was telling her otherwise. Swan had her mind set to the fact Andrew had caused the explosion, accidental or not, which led to the pair having multiple, long, one sided conversations and then a budding friendship.

They talked on and on, exchanging stories of corpses and different acids while drinking coffee, until Emma's phone went off. She picked it up and looked at it, furrowing her brows.

"Oh, got to go. Detective Hard-ass summons," She said rolling her eyes, but they held the unmistakable glimmer of excitement.

"Yes, well you should tell this Detective Hard-ass to send me some photos of a dead mangled body," Andrew said as Emma stood up. Emma raised her eyebrow at this last comment. Andrew laughed.

"Okay, fine, but call me in if one of your forensics gets a whiff of.. chlorophyll or something," Andrew said, smiling. Emma laughed.

"Will do!" And with that the yellow bug flew off in the direction of the next crime scene.

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

Detective Inspector Catherine Rollins was one of the best inspectors of the NYPD. Her incredible track record put her on some of the most difficult cases in the city. She was currently at the site of one of the latest baffling crimes. The scene was flooded with people in contamination suits, and officers digging around for information.

A yellow bug pulled up outside the small bakery. The young blonde haired woman got out of car, ducked under the police tape and ran up to Catherine.

"Hey, what do we got?" Emma asked Catherine. She and Emma started walking further into the bakery as Catherine started to describe the crime.

"Break in at 21:00 last night, nothing stolen, just a lot of broken windows and crushed scones," Catherine began.

"A break in? That's all we're here for? Where's the owner," Emma asked.

"Well that's just the question of the day, isn't it?" Catherine said.

"What?"

"The owner she's gone. Suspected to be dead, but no body, no traces, nothing." Catherine said grabbing a contamination suit and thrusting it at Emma.

Emma let out a breath, and hastily stuffed the suit on. She and Catherine made their way over to where a forensics person was crouching on the ground.

"Anderson," Catherine said in acknowledgement of the man. "What've you found?"

"There are traces of smoke left around the air, the fire alarm has been smashed," Anderson started in his nasally voice. "And we've found traces of ash here," He held up a clear bag with ashes in them.

"They're being examined now?" Catherine asked. Anderson nodded. "Good." Emma and Catherine moved to the side to make way for a photographer, documenting for the police report.

They crouched down and put latex gloves on. Emma picked up a pinch of the ash, Catherine doing the same. "The killer's probably burned the body. We'll see if the DNA match is Marian Locksley, the owner." Catherine assessed.

A frown formed on Emma's face and she raised her head. "But, if the killer's burning the bodies, why is there so little ash?" she asked. Catherine and Anderson raised their heads as well.

"The killer probably just scattered it," Anderson said. He pointed to the shattered window. "The glass is busted, the wind probably moved them around. Emma nodded as she and Catherine stood up.

"Alright.. so, what was the motive?" Emma asked. Catherine shook her head.

"Haven't the faintest idea. We're running a background check but at the moment, we know she's just a baker," Catherine said. "She's married to one of our officers," Emma's head snapped up.

"Marian Locksley, you said? Oh god..." She trailed off and closed her eyes. "She's Robin's wife." Catherine nodded sadly as she and Emma walked around to examine the scene a bit more.

"Hey what's this?" Emma asked picking up a sheet with pictures of people. Catherine walked over to her.

"Oh, that's a list we found as evidence. Apparently, Marian kept track of her best customers and picked a customer of the month," She pointed to a larger picture tacked to the wall, under the heading 'Customer of the Month' and surrounded by gold stars.

Emma raised her eyebrows and Catherine shrugged. "I don't know. Some sort of marketing trick, I guess." Emma flipped through the list again.

"Walter Perry, Kim Rallings, Ingrid Neva, George Stanley... Do we even need this?" Catherine shrugged.

"We'll keep it as evidence of course, but since we can question one of our officers for potential murder motives, it's not really of help to us." She replied. Emma nodded and walked off to survey the rest of the crime scene.

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

For the next couple weeks, Emma and Catherine were still stumped on their case. They had confirmed that the ashes were indeed Marian's, but they still couldn't locate any motive or incentive for her murder.

Emma was just filling up the report when the phone rang. Before Emma could reach for it, Catherine picked it up.

"NYPD, DI Rollins speaking. Yes... what address? Alright we'll be there. Close off the area." Catherine put the receiver down. Emma looked at her inquisitively. "There's been another break in. The building is trashed but there's no body,"

Emma raised her eyebrows. "They found ashes though," Catherine finished, grimly. Emma frowned and put down her files.

"It's related then." Emma stated. She and Catherine picked up their badges and firearms then walked out of the station where the squad car was stationed.

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

When DI Rollins and Sergeant Emma arrived at the scene, the police were crawling everywhere. The break in was on a busy street so mostly, they were trying to block the scene from civilians.

A police man nodded to them and lifted the caution tape to allow the detectives through. Many forensics people were walking around the scene, clothed in blue contamination suits. The bright flash of cameras lit up the grim department store, and ashes lay scattered everywhere.

Racks of clothing and merchandise were thrown awry across the floor. Anderson was there once again. He was collected a swab of something on the ground.

"Anderson," Catherine called. She and Emma walked up to him.

"There's blood this time," Anderson replied. Catherine spotted the small amount of red liquid on the floor. Emma turned around and looked at the ashes that lay on the floor.

"Did you confirm a DNA match?" Emma asked. Anderson nodded his head.

"Yeah, it's working right now." Emma frowned and surveyed the ashes one more time.

"There's the same amount as last time," She said. Catherine raised her eyebrows. "Last time it was supposedly the broken window, but this window's not broken," Emma concluded. Anderson huffed.

"It's a department store," He said condescendingly. "They seem intent on blasting the air 24/7," Emma frowned at him but said nothing more. Catherine was looking at the ashes.

"Still take note of that Sergeant Swan," Catherine said to Emma. "You never know what information you'll overpass at a crime scene."

"I just got a DNA match," Anderson announced "your victim is one Mr. Ari Haswari"

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

Robin Locksley sighed and stared down at his pile of paper work. The bags under his eyes seemed to stand out more than ever since his wife, Marian, went missing a while ago. He, himself was a member of the police force, but they haven't gotten anywhere on the case of his wife's disappearance.

"Ugh," Robin huffed, trying to write up a report on his last arrest. The doors of the New York Police Department slammed open and a woman with jet black hair and stunning brown eyes flew inside.

"Help me! Somebody, please!" The woman cried. Robin came over to her.

"Milady? What's happened?" Robin asked leading the woman to his desk. The woman had tears streaming down her face.

"M-my fiance, Daniel, he's missing and I can't find him anywhere!" She stuttered.

"Okay, calm down. May I ask your name?" Robin asked. The woman sniffed.

"R-regina. Regina Mills," Regina said.

"Okay Regina, are you certain there's no place your fiance might be?" He asked. Regina shook her head vigorously.

"No, I've checked every place! I called all our friends, his boss, his co-workers..." Regina trailed off, her face twisted in misery.

"Perhaps-" Robin began.

"No!" Regina cut in. "I know Daniel! He always calls if he's going to be late. He doesn't drink, so he never forgets to, and I haven't seen him for two days! He hasn't shown up for work, and he never shirks on responsibilities. He-he's hurt, I know it! Oh god!" Regina held her hand over her mouth, her body racked with sobs.

Robin placed his hands on her shoulders in a gesture of comfort. "Shh, you need to calm down Ms. Mills,"

She clung to his shirt and continued sobbing hysterically. Robin felt a sudden bout of sympathy for this young woman and proceeded to calm her down and inquire about her missing fiancee.


	3. Chapter 2

**Chapter 2**

"Ah good you guys are back" Robin said, standing from his desk and walking towards Emma and Catherine as they strolled into the squadroom after a trip to the latest crime scene, and then the forensics lab.

"What happened?" Emma question skeptically.

"Can't I just be glad you two are back safe? Something bad has to happen for me to be happy you're back?"

The two women shared a look before turning back to him. "Yes." they said in unison as they turned around.

"Ugh, fine. Something did happen but its not, err.. EXTREMELY bad."

"Officer Locksley, withholding information is a federal crime." Catherine said sharply. Robin held his hands up in defense.

"Okay, okay," He said grabbing a sticky note from his desk. "Well a woman came in while you were out. Said her name was 'Regina Mills' and her fiance 'Daniel Stabler' was missing. I thought he might be one of the victims from your case." Robin finally said, reading the names from the sticky note.

Just then Catherine's phone rang, she excused herself and walked back outside before answering it.

"Hey Dad," She said putting her phone up to her ear.

"Hey sweetheart. I was wondering if you were free for lunch in couple hours."

"Umm. I guess I could find sometime, there's just this case and…"

"Yeah, I know all about your case. It's actually why I need to see you."

"Oh… Okay. Wait is everything ok? Are you ok?!" She questioned, getting a little worried.

"Yeah, yeah everything's fine. I'm fine. I just think I might have some information but I don't feel comfortable sharing it over the phone."

"Are you ever not going to take extreme precautions?" she joked knowing that it was her father's job to be cautious with information.

"As long as I'm an Admiral for the U.S. Navy I will always be cautious, especially over the phone."

"Yeah, Yeah, Yeah. Anyway I should get back to work. I'll see you later."

"Ok sweetheart, see you later. Love you."

"Love you."

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

"Hey!" Emma called out as she let herself into Andrew's apartment. She's done this on multiple occasions. A smile spread on her face as she sidestepped all the chemistry equipment strewed about the room.

In her hands she carried a fairly heavy Amazon package. "I found a package outside!" She called. Andrew's head popped out from the kitchen where he was currently making lunch for himself and Emma.

When he saw the package his eyes lit up. "My silica beads!" He motioned to the coffee table. "Just set them there, thanks. I was hoping I'd be able to make liquid glass today!" Emma wrinkled her face in confusion.

"Wha- you know what? I'm not gonna ask," She muttered and made her way to the kitchen. She sat down at the table pushed a chemistry textbook out of the way.

"Jesus, you're insane about your work," Emma said. Andrew smiled.

"Well, it's never _insanely_ boring,"

"Hence the textbook..."

"Well your work's no hoot either,"

"I know. Dead bodies? Yawn!" Andrew rolled his eyes and set two sandwiches on the table.

The pair ate in silence for a few minutes before andrew finally spoke up.

"Hey, Em. I want to get something nice for Alyssa. It's our 1 year anniversary next week and I have absolutely no idea what to do. Will you help me?"

"Of course. Ooo I got it! How about a nice piece of jewelry. There's a new jewelry store right over on Weston road."

"Yeah, okay. I'll take a look."

"I know. You should get her a diamond necklace."

"I don't kno…"

"A diamonds a girl's best friend remember."

"Yeah, yeah, yeah. Whatever."

"Hey you're the one who asked for help."

"True. But do you really think…"

"Yes, I do."

"How did you…"

"Not that hard."

"Okay, you really need to let me finish at least one sentence."

"I let you finish that one."

"You know what…" Andrew said has he picked a chip up off his plate and threw it at her.

"Hey." She said throwing a chip of her own as they both started laughing uncontrollably.

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

Catherine smiled to herself as she pulled up to the small cafe, in her blue corvette. Seeing as this wasn't an official meeting She saw no reason why she couldn't drive her own car for once.

As Catherine entered the cafe, she found her father quickly as he was the only one in standard Navy issue dress blues with every last aspect perfectly up to code. She shook her head slightly at the man with a smile on her face and she made her way through the room to the table by the large window.

As Catherine approached, the man turned his head and upon seeing her, stood to greet her with a hug.

"I was starting to think you wouldn't show." he said

"Sorry, Emma and I were checking out the house of a possible victim."

"Possible victim?"

"Yeah, apparently some woman came in and said her fiance was missing. Officer Lockesley thought that with the sudden disappearance he might be a victim of our serial killer."

"Any proof at the house?"

"Just some ash."

"Ash?"

"Yes, but that's a detail I can't discuss. Anyway what information do you have?"

"That's it? No chit-chat? Can't I just visit with my only daughter after a long trip in the middle east?"

"Well I guess. But Dad you didn't even tell me you were back. There was no call, no email, nothing."

"True, but I called today."

"Yes, _to share information _not to 'chit-chat'."

"Okay fine, you win. Anyways after I got back I received a call from a SEAL, William Harrington..."

"Whoa, whoa, wait. The same William Harrington that you tried to set me up with."

"Yes... But that's beside the point." he said as Catherine rolled her eyes. She let him continue without voicing some sort of snide remark. "Billy called to ask if I would help him with something, and I said I would. The catch being I couldn't know what it was until I met him at his apartment the next day."

"Why would you agree to that?"

"Because unlike you I actually have faith in people."

"I have faith in people." Catherine said defensively "I have faith in Emma and Robin."

"But not in Billy?"

"Yeah but Billy's an ass."

Admiral Rollins just laughed at his daughter's bluntness before continuing the story. "Well faith didn't matter because when I got there, he was nowhere to be found. Now, 2 days later, still no sign of him. It's like he just vanished,"

"Just like the other victims."

"Exactly. That's why I called you."

"Okay I'll look into it."

The two spent the next hour catching up, before Catherine got a call and had to head back to the precinct.


	4. Chapter 3

**Chapter 3**

"Exactly when are you going to get rid of this deathtrap you call a car?" Andrew asked Emma, nervously glancing around the inside of her yellow bug.

"Shut up." Emma said, "You have to be nice to me." Andrew raised his eyebrow.

"Do I?"

"Yes. I'm risking the wrath of detective hard-ass by driving you to this damn jewelry store, so yes. You owe me."

"I thought you and Catherine were friends? What's with the names you big bully?" Andrew teased. Emma scoffed.

"It is a very affectionate pet name I adopted for her!" She cried defensively. Andrew laughed.

"I'm sure she _loves_ it,"

"You're the one who needed a lift because you decided the cables that _actually run your freaking car_ were put to better use in one of your inane experiments." Emma pouted and pulled up in the small store's parking lot.

"It _was._" Andrew insisted, getting out of the car.

"And this is why your car insurance company hates you," Emma said. Andrew rolled his eyes and walked into the jewelry shop.

The bell rang as the door to the shop was opened. The store's owner looked up from the inventory she was currently tending to. She was a beautiful woman that was probably in her twenties and had long blonde hair pulled into an intricate bun. She smiled at her two new customers.

"Hello! How may I help you today?" She asked.

"Oh, I'm looking for a present for my girlfriend," Andrew said walking over towards her.

"Oh! I think I have just the thing." The jeweler walked up to a glass case and pulled out a ring with a small diamond inlaid in it. She held it up for Emma and Andrew to see.

"Well that's actually pretty-" Andrew started.

"Nope." Emma interrupted. Andrew looked at her questioningly. "This one here," She continued gesturing to Andrew. "Is quite the doofus. We're gonna need something bigger." Andrew looked appalled.

"You know, that could be taken as slightly offensive!" He protested. Emma shrugged.

"Well it's true,"

The shopkeeper looked amused as she watched the two friends bicker and pulled out a sapphire necklace in the shape of a flower.

"How's this?" The jeweler asked. Emma inspected the goods like the true sergeant she was. When she finished she nodded in approval.

"Yup, this should calm Alyssa down enough."

"Wha- calm Alys- What's wrong with Alyssa?!" Andrew asked. Emma looked at him.

"Your last experiment..." She prompted, hoping he would be able to figure it out.

"Yeah, what about it?"

"It kind of exploded everywhere..."

"Well Alyssa's usually fine with my experiments."

"It ruined her dress..." Emma said, exasperated.

"Ouch!" The jeweler winced.

"Her _Chanel_ dress " Emma said looking pointedly at Andrew.

"Double ouch!" The jeweler cried. Emma nodded her head in agreement. "I think you're gonna need the matching earrings." Andrew just looked at her, still confused.

"Really? Because I could just-"

"Take the earrings!" Emma and the jeweler said in unison. Andrew held up his hands in surrender and started to pay for the necklace and earring pair. Emma surveyed the jeweler.

"I like you," Emma said. "You have common sense which is the only quality my friend here lacks," Andrew was about to interject, but decided against it and just grumbled to himself. Something about 'ungrateful, so-called friends'.

The jeweler smiled. "Why thank you,"

"What's your name?" Emma asked.

"Ingrid Neva,"

"Well Ingrid, we'll be sure to come back to this store again!" Emma said.

"Thank you! Oh! Actually we're getting a new shipment of goods next week, you might want to stop by. I think some of those items would really suit you." Ingrid said.

"Thanks! I'd love to but I'm swamped with this new case right now. I don't know if I can get time off again. When does your next shipment come in after this one?" Emma asked.

"We get new shipments every eight to nine months, but I'm sure if I put the jewels on hold you wouldn't have to wait that long." Ingrid offered. Emma smiled.

"Thanks! I appreciate that! I'll be sure to come a soon as I can! See you soon!" Emma called as she was literally dragged out of the store by Andrew.

"Goodbye Ms. Ingrid, thanks for the help!" Andrew called over his shoulder. Ingrid smiled and waved them farewell.

Emma and Andrew drove away from the little jewelry shop on Weston street with smiles on their faces.

"Now that is what I call a successful shopping trip!"

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

Andrew struggled with the keys to his apartment as he and Emma arrived back home. When he finally got the door open Emma walked in and threw her briefcase on the table.

"I can't believe you just left a briefcase full of evidence in a car that has a very weak security system. How are you still employed?" Andrew complained. Emma rolled her eyes.

"I knew we wouldn't take that long. You were the one shopping," She said simply, flopping into a chair.

"I think I should be insulted."

"Well, you're a guy. Guy's are very... how should I say it? _Simple minded."_

"Okay, now I am offended."

"Oh, you know it's true." Emma took out some files from her briefcase and Andrew sat down next to her. "Here, you owe me. Solve the case." Andrew took the files from her.

"Is this even allowed?" He asked.

"What?"

"Showing some lowly civilian police reports?"

"See now, then you just insulted yourself." Andrew rolled his eyes.

"Well," Emma said, answering his question and popping a piece of gum in her mouth. "Not _technically. _But if we get caught I'll say you stole them from me and make you take the fall."

"Hm." Andrew said. "So normal protocol."

"Yup." Emma said popping the 'p'. Andrew nodded and opened the files like this was _totally normal. _

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

"Daaaaaaaaaamn," Andrew said, files spread out everywhere.

"Yup,"

"This is..."

"Yup,"

"Wow!" Andrew was completely blown away by the case. "This is like a crime from a movie! Or-or a book! I mean you're like James Bond! No-no, James Bond doesn't do mystery... Oh! You're like Sherlock Holmes! Kicking ass at 221b Baker Street with your highly intelligent deductions and-"

"O-OK! HEY! Cool it with the geeking out." Emma interrupted Andrew's excited rant. Andrew frowned.

"Whatever," He pouted. "I'm still gonna call myself Watson,"

Andrew and Emma spent the next... who knows how many hours looking through all the notes on the case so far. The sun was setting by the time Emma's phone rang with an angry text from Catherine, and then a sorrowful text from Robin.

"Flippy-flubber-floppy-flapjacks!" Emma cried jumping up. Andrew raised an eyebrow.

"What are you? Ten? Can't curse huh?"

"Shut up! I'm dead! Crap, crap, crap, crap, craaaaap!" Emma yelled as she hastily threw on her red leather jacket and collected all her files. "Robin was covering for me but I was supposed to be back before Catherine came to the station! I'm dead."

"Okay, Drama Queen," Andrew said.

"SHUT UP! THIS IS YOUR FAULT!" Emma yelled.

"I know," Andrew sighed. "Everything in the world is my fault. World hunger is my fault, global warming.. even the fact that we can find another life form outside of Earth! Oh hang me now for my sorrowful treason!"

Emma glared at him. "I'm the drama queen, huh?" Andrew smiled and waved goodbye as Emma raced to the station to face an angry Catherine.


	5. Chapter 4

**Chapter 4**

Two weeks had gone by and there were no new leads. Emma, Catherine and Robin all sat at their desks with nothing to do.

Suddenly a tall man about 6'2" stormed into the police precinct, he was wearing his Navy Dress Blues and removed his hat as he burst through the double doors.

"I demand to speak to the person in charge of the disappearance of Lieutenant Commander William Harrington" the man stated firmly.

Robin and Emma suddenly jumped from their chairs in surprise, while Catherine rose slowly and approached the man.

"That would be me, DI Rollins" she said, was it wrong that the first thing she noticed about the man was his crystal blue eyes?

"Well detective, my name is Lieutenant Commander Steve McGarrett. It has come to my attention that the NYPD has not been able to do its damn job and locate my fellow SEAL!"

"Sir, I can assure you we are doing all we can to find your friend," Catherine said remaining calm despite the man's angry ranting.

"Like hell you are! I should just tell the Navy Criminal Investigative Service to take this case away from you!"

"I would strongly advise against that, even though I don't know what that is. We believe that Mr. Harrington's disappearance is one in a string of recent abductions. Removing us from the case will just make it impossible for us to ever find your friend."

"Lieutenant Harrington!" He snapped. Catherine nodded her head in acknowledgement of the correction. Then, Commander McGarrett's eyes softened, and they held a sad and tired shine.

"I guess you're right, I just… I don't know…" the commander stuttered "You know what? I'm sorry, the NYPD does need to take this case"... he started again but was quickly cut off by Andrew bursting through the squad room doors.

"Emma, Catherine!" he called, and the two women ran to his side stopping him before he had the chance to trip over Officer Locksley's desk.

"Whoa, whoa, whoa. Slow down. What's wrong?" Emma questioned.

"I figured it out" he huffed, clearly out of breath.

"What? What did you figure out?" Emma said concerned about her friend's state of mind.

"The case. Your case, I found out why there was so much ash around the crime scenes."

"What do you mean? We know why there's ash, the killer's burning the bodies." Catherine said somewhat confused.

"Yes! Yes, but that's not where it stops. The killer is turning them to synthetic diamonds."

"What?" The two women said in unison with matching confused looks on their faces. They were used to Andrew jumping to random conclusions that usually don't make sense at first, but this was just outright irrelevant.

"Didn't you wonder why there was so little ash at the crime scenes?" Andrew asked. Emma and Catherine nodded.

"Yes, Anderson, our forensics guy pointed that out. He told us it was probably just swept away and scattered." Catherine said.

"Yeah well fire him." Andrew said. Emma looked confused.

"Okay, so the killer is collecting the ashes," She deducted, "But how the hell does that relate to diamonds?"

"Well you see…" Andrew started pushing past them towards the whiteboard, while Emma rolled her eyes "Carbon" he stated as he wrote it out on the board

"C, a non-metal, element number 6, 12.0107 amu, 6 protons, 6 neutrons, 2 energy levels, and 5 isotopes" he began to rant. "but do you know what makes it important to your case?" he turned to face Swan and Rollins, but instead came face to face with them, plus a small crowd that had gathered, including Officer Lockesley and Commander McGarrett.

"_No_. We cannot all follow your train of thought." Catherine said with attitude and venom in her voice.

"Right." Andrew replied defeated, as he turned back to the board. "Well, once I figured out the ashes were taken by the killer I couldn't stop wondering what he would do with them."

"Yes, but how did you get to diamonds?" Officer Locksley asked in his british accent. His face was little pale, considering they were talking about his late wife.

"Well what would you want to do with a bunch of human ashes?" Andrew asked. "Think about it, you could just get rid of them, but then why wouldn't you just leave them where they are?"

"Well, so that you couldn't identify who the victim was." Emma said. Andrew shook his head.

"No, if the killer really didn't want us to know who they killed, they would've made sure to get all the ashes and not leave any behind. And they definitely wouldn't have killed and burned them in their own homes and businesses." He pointed out. Catherine frowned.

"I still don't see how you got to diamonds, that's not even possible." Said Catherine. Andrew directed everyone towards his trusty whiteboard again.

"No, it is! Diamonds are made of carbon, and carbon is in the human body, right?" Andrew asked his attentive, and somewhat confused audience.

"Uh... is it?" Emma asked. Andrew huffed.

"Yes, it's the element that makes up 18% of the human body, second to oxygen." Andrew only got blank stares. "You know... the human body is 65% oxygen, 18% carbon, 10% hydrogen, 3% nitrogen... No? You never learned that? Oh dear lord, you're teachers apparently need to be fired too." He shook his head in disappointment.

Everyone else just looked slightly agitated. Andrew ignored this fact and turned back to his whiteboard.

"So, since human ashes can be turned into diamonds, you have your motive!" Andrew said proudly. Emma frowned thoughtfully.

"Then our murderer is a jeweler?" She concluded.

"Great, that narrows it down to just about half the population." Commander McGarrett interjected.

"Well, not necessarily.." Andrew said. Catherine raised her eyebrows.

"How do you say?" She asked.

"Well, diamonds from ashes take quite a while to develop. You have to heat them, set them, cut them.. it's not a simple process."

"Okay then how long does it take?" Catherine asked.

"Well first you have to find a crucible that can withstand incredibly high heats which is a task in itself, and then once you allow the other elements to oxidize, turn the carbon to graphite - Oh! You can't forget the metal catalyst and diamond seed with -"

"O-ok, ok, Hey!" Emma waved her hands around, cutting off Andrew. "Speak. English." Andrew huffed.

"Ok, should I just explain it to you?"

"Yes, that might be a bit helpful," Catherine said sarcastically. Andrew erased his precious whiteboard and started again.

"Okay, so the diamonds are made of carbon and there's carbon -" He began.

"Yes, yes, we know this. 81% blah blah. _Fast Forward._" Emma nagged him. Andrew frowned.

"18%" He corrected under his breath. Emma shot him a glare. "Anyways... I'll explain this step by step."

He spelled out 'step one' on the whiteboard. "Okay step one. You need to collect several ounces of ash and put them in a crucible that withstands inflated temperatures. A crucible is a metal or ceramic container, and it allows other substances to melt or be exposed to heats."

Andrew wrote out 'step two' on the whiteboard. "Now, you bring the crucible to just over 5,000 degrees fahrenheit and allow all elements except carbon to oxidize." He looked at everyone to make sure they were following. "Oxidation means the loss of electrons." He clarified.

Catherine seemed a little indignant at being told what oxidation is, but before a snide remark could leave her lips Andrew quickly whipped back around and wrote 'step three' on the board.

"Now step three is a little bit of a longer process. You have to continue adding heat to the carbon for a few weeks, until it becomes graphite."

As Andrew wrote out 'step four' on the whiteboard he began to explain it; "Once you have graphite you place it into a core with a metal catalyst." He turned around to explain, "a catalyst increases the rate of a reaction"

Turning back to the board he continued "You will also have to place a diamond seed crystal in the core. Once this is done place the whole thing in a diamond press have the temperature at 2,500 degrees fahrenheit and the pressure at about 800,000 pounds per square inch, and just let it sit for a few weeks. And whalah you have a diamond" As he finished and spun around to face the crowd with his arms spread outward with dramatic flair.

Catherine, Emma, Officer Locksley, and Commander McGarrett stood there gaping at Andrew, completely flabbergasted.

"And this is why he was the Chemistry teacher's pet," Emma mumbled under her breath to Catherine. She just nodded her head, still a little shell shocked.

"O-okay, so now we know _how_ the murderer did it, so what? We just look for who orders these items and we have the killer?" Officer Locksley said. Andrew, Catherine and Emma just stared at him. "Oh... that's cool... yeah that's... good..."

"Wait!" Emma said. "You-the ..and the- jewels...heh..."

"You're a detective of the NYPD. Speak clearly Sergeant!" Catherine said sternly.

"Andrew!" Emma finally got her words together. "You were shopping for a diamond necklace for your girlfriend!" Andrew looked puzzled.

"Yes, Emma what does that- Oh!" Andrew cried as realization dawned on him. Emma spoke into her walkie talkie.

"This is Sergeant Swan, we have a lead. Send back up to 198 Weston Road. I repeat, 198 Weston Road."

Catherine looked confused as Emma and Andrew started heading for the squad car.

"The jeweler," Emma started without any prompting from Catherine. "She said she gets shipments every 8-10 weeks, about how long it take to make a diamond." She, Andrew and Catherine got in the squad car and Emma began speeding towards 198 Weston Road.

"Yes, but that is not enough evidence for an arrest, different jewelers have different inventory." Catherine said.

"Are all of them regulars at both the Locksley Bakery and Mifflin Stables?" Andrew asked solemnly. Catherine's eyes widened.

"Just what was this jeweler's name?" She asked as the car rounded the corner, its sirens blaring loudly.

"Ingrid Neva." Emma said.

"I'm going to need you to speed up, Sergeant Swan."


	6. Chapter 5

**Chapter 5**

With Ingrid in custody Emma and Catherine had to come up with an interrogation strategy quick if they wanted to keep her there. Given that there was a suspicious lack of evidence they were going to have to get a confession out of Ingrid, which would definitely not be easy.

Robin walked up to Emma and Catherine. "Hey," They both nodded in acknowledgement. They were all standing on the opposite side of one-way glass, looking into the room that held the suspect.

"Why do you think she's the killer? I mean besides the whole jeweler thing..." He asked.

"Ingrid's name was listed on Marian's 'best customer's list', and when Andrew and I saw her, she was wearing the same scarf as me." Robin raised his eyebrows.

"Same scarf?" He asked, confused.

"I just happened to purchase this scarf from the department store where our second victim was found.. or their ashes were found. I'm sure that can't be a coincidence." Emma said. Robin widened his eyes.

"That is... really not enough evidence to go on!" He said in a hushed tone.

"I know," Catherine intervened. "That's why we need evidence, and fast. Contact the department store and tell them to scan their systems for any customer under Ingrid's name. When you're done try and obtain a search warrant for her residence." She said this last part to Emma. Emma nodded.

"Right,"

"And Robin, contact the Navy Base where Billy Harrington was stationed. Ask them to scan their recent visitor's list. See if Ingrid's listed." Robin nodded.

Both he and Emma walked out the doors of the interrogation unit and drove off to their assigned destinations.

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

It had been over 3 hours since they brought her in and Ingrid hadn't said anything, she hadn't even asked for a lawyer, or even a glass of water.

Catherine was standing in the room next to the interrogation room staring down Ingrid through the one-way glass, when Andrew bounded into the room.

"Hey Catherine have you seen Emma?" He questioned.

"Yeah, she left about 20 minutes ago to check for evidence and see if she could obtain a warrant to search Ms. Neva's house."

"Oh ok." Andrew said in disappointment, turning to look through the glass.

Catherine crossed her arms and turned to Andrew.

"Now... I was just wondering.." She began. Andrew raised an eyebrow in inquiry.

"Hm?"

"You told us how to make a synthetic diamond from human ash." Andrew blinked.

"...Yes..."

"You told us off the top of your head. In fact, you told us in so much detail it's like you were an expert on it." A smirk was playing on the corner of her lips.

"Well, it's kind of in my field. You know, the whole _chemist_ ordeal?" He got no response from Catherine other than a raise of an eyebrow.

"Chemistry usually doesn't imply explicit knowledge on manipulating dead human bodies." Catherine said simply.

"..."

"..."

"Oh! Come on!" Andrew spluttered. "You can't _really _be implying that I spend my free time with corpses, can you?! I seem to recall that being in _your _job description, not mine!" He was completely flabbergasted until he caught the mirth shining in the Detective Inspector's eyes. "Oh..."

"Are you that lacking in the field of humor Mr. Lerario?" Catherine teased. Andrew huffed.

"Oh, shut up,"

Just then Catherine's phone rang. Looking down at the screen, she saw that it was Emma.

"Hey, did you get the warrant?" Catherine said as she accepted the call.

"What no greeting? Just straight to the point?"

"I said hey" Catherine replied defensively. "Anyway did you get it?"

"Yes I got it, but I don't actually know what any of this stuff actually looks like."

"Why don't you have Andrew go down there with you?"

"Because, he won't answer his phone."

"Well he's right here want me to ask him?"

"Yes but do something for me first."

"Sure, what do you need me to do?"

"Gibbs-slap him for me."

"Gib-what?"

"You really need to watch more TV. Just smack Andrew upside the head for me."

"Okaay?"

Catherine did as she was told making one very unhappy Andrew.

"What was that for?!"

"For ignoring Emma." Catherine said before returning to her phone call. "Ok done do you want me to send him down there with Robin?"

"No I think you should come down here too." Emma said as she took a step into the apartment and saw pictures of each victim on the wall. "If we didn't have enough evidence before we do know."

"Ok we'll leave right now." Catherine hung up the phone and turned to Andrew "Emma needs us at Ingrid's apartment."

"Us?" Andrew questioned skeptically.

"Yeah, us. Emma says she needs your help to identify the materials used in diamond making."

"Ok"

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

Seeing as there were no squad cars left Catherine was able to drive her own car once again.

"What's with you, Emma and old cars." Andrew said as he shut the car door after he sat down.

"I don't know. I guess we both just like the feel of a classic type of car."

"Whatever, old cars are just death traps."

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

After 15 minutes of looking through the apartment Andrew was able to find and identify all the materials used in making Diamonds.

Once Emma and Catherine took a better look at the wall covered in picture they found that certain parts of some pictures were circled, like Marian's butterfly clip and Billy's shark tooth necklace. Surrounding the photos the words 'They killed her' and things like 'HERS' with an arrow pointing towards one of the circled accessories.

"Ok so who's 'Her'?" Emma asked.

"I don't know. But something tells me that if we figure it out we'll have motive."

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

Emma and Catherine entered the interrogation room ready to put Ingrid behind bars. Emma sat across from Ingrid with a thick case file, while Catherine stayed back leaning against the wall with her arms folded across her chest.

"Ingrid," Emma greeted coolly.

"Emma. You never did come back like you promised," Ingrid said in a sickly sweet voice.

"Oh that's right, you said you had some things you thought would suit me. So you think I would look good covered in dead bodies huh?!"

"That's enough Sergeant," Catherine interrupted Emma.

"Yes, do listen to your commanding officer. I'm sure the title of Detective Inspector goes much farther than Sergeant." Ingrid taunted. Emma narrowed her eyes but kept her mouth shut.

"Alright Ms. Neva. This is a recording tape, as you know. It's been on for several hours but you don't seem to be very cooperative. Do you know why you're here?"

"You believe I killed some people, correct?"

"Yes. We have reason to believe you killed 4 people." Emma stated as she started to place photo of each victim in front of Ingrid. "Marian Lockesly, Ari Haswari, Daniel Stabler, and Lieutenant William Harrington."

"I don't know any of those people."

"Wrong. You were a regular at Marian's bakery, you shopped at Ari's department store, you went to Daniel's stables all the time, and you made multiple visits to the base were Lieutenant Harrington was stationed."

"That's just speculation. You can't prove I did any of this."

"Actually, yes we can," Catherine said stepping into the conversation. "We got a warrant to search your apartment and our chemistry expert found all of the equipment used to turn human ash into a synthetic diamond. We also found a wall covered in photos of the 4 victims."

"But you… you don't understand… you'll never understand. The killed her… they… they killed her."

"We know all about your little sister Ms. Neva. And these people had nothing to do with her death."

"You don't know what you're talking about. They killed her. They killed my little sister!" Ingrid began to get angry.

"Your little sister, Helga. She died of cancer. No one killed her."

"NO! You're wrong! They killed her! Those 4 killed her!"

"Ms. Neva calm down." Emma interjected, "Detective Rollins is right, your sister died of natural causes."

"That can't… that's not possible."

"I'm sorry Ms. Neva." With that Emma stood collected the photos and walked out of the room, with Catherine close behind her.

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

"So what happened with Ingrid" Robin said as he approached Emma and Catherine standing by their desks.

"She basically confessed, so she'll get sentenced for 4 counts of murder in the 1st degree. She seemed to think the victims had something to do with her sister's death. The accessories they wore probably linked to her sister. They were circled in her apartment." Emma answered.

"So basically she'll be in prison for 4 life sentences, and we'll never have to deal with her again?"

"Basically." Catherine said.

"I don't know about you guys but I'm gonna go home take a nice long bath and actually sleep for the first time in like a month in a half." Emma said and the trio headed towards the door.

"Same here, I could really use like 3 days worth of sleep." Catherine said as they parted way towards their cars.

"Oh yeah don't expect me here on monday, Catherine." Robin half-shouted as he stopped at his car

"Wasn't planning on it."

And with that they all got in their cars and drove off.


	7. Epilogue

**Epilogue**

Emma and Catherine sat at a table in a small shawarma restaurant trying to find anything to talk about that wasn't the case they just closed.

"So, Commander Mcgarrett…" Emma started, hoping to get Catherine to reveal something.

"What about him?"

"Well you like him, don't you?"

"I have no idea what you're talking about. Besides even if I did it would be against regulations since he was considered family of a victim and he works with my dad, and I've learned from experience never to date anyone that works with my dad."

"So you're telling me you didn't obtain his number and you didn't put little hearts next to his name."

"No I didn't, I'm not a 14 year old. Anyway what's with you and Andrew?"

"Eww thats weird he's like my best friend, plus I have boyfriend."

"Oh really now."

"Yes he's a tall, handsome pirate with a hook for a hand and wears a leather jacket."

Catherine gave her a confused and skeptical look.

"I'm kidding he's ex-military with a prosthetic hand."

"Ok whatever you say."

Just then Catherines phone, which lay on the table, buzzed to life as she received text. Knowing quite well who it was Catherine quickly locked the screen before the other woman could see.

"I saw that." Emma said with a smirk.

"You saw nothing."

"Oh really now" Emma said mockingly as she stealthily grabbed the phone off the table

"Hey give that back"

"Nope." Emma said as she unlocked the screen to read the text. "Ooo looky here. 'From: Steve McGarrett *football emoji* *boat emoji*', well excuse me miss I'm not a 14 year old…"

"Shut up." Catherine said making a grab for the phone, but Emma quickly pulled it out of reach.

"Nuh-uh, we still have to read the message. 'Hey Cath heard the case was closed. I was hoping we could hang out again before my next deployment. I had fun last night. - Steve.' Again? Last night? What happened last night? And what's with the pet name"

"Nothing! I swear! We went to dinner, that was all. And I told you he works with my dad, my dad refers to me as Cath a lot so he probably just heard it from him."

"Whatever, you still lied to me."

"I was keeping a secret there's a big difference."

"Yeah, yeah whatever." Emma said tossing the cell phone back across the table. "I still think my pet name's better. Catherine narrowed her eyes.

"And what's your pet name for me?" She asked suspiciously.

Emma evaded Catherine's eyes. "Err..."


End file.
